Cancer 'Vaccine' for Advanced Disease Passes Early Hurdle

WEDNESDAY, April 16, 2014 -- Researchers report early progress in developing a treatment that might one day help the immune system defend itself against cancer.

The results of their study -- the first of three stages of research required of drug treatments in the United States -- suggest the treatment is safe. But they don't prove it works or which patients it could help. Nor do the researchers offer definitive details about factors such as cost.

Still, the findings are an example of "really sexy science" that holds promise, said Dr. Elizabeth Mittendorf, an oncologist and associate professor at University of Texas MD Anderson Cancer Center in Houston, who was not involved with the study.

Willem Overwijk, also an associate professor at the Anderson Cancer Center, cautioned there are several caveats that could prevent the experimental treatment from becoming a successful medication.

The treatment is known as a cancer vaccine. These "have been promising without really delivering for decades," Overwijk said. "They are intended to activate the immune system to seek out and destroy cancer cells. So they are mostly intended for patients who already have cancer, and not preventively."

Because each cancer type is unique and typically requires a different vaccine, "a preventive approach would require dozens of different vaccines to be given to cover all cancer types," he explained.

The treatment under study aims to enlist so-called "dendritic" cells in the immune system, according to the study, published in the April 16 issue of Science Translational Medicine.

"Dendritic cells are the sentinels of our immune system," said study co-author Tibor Keler, chief scientific officer at Celldex Therapeutics Inc., which funded the study. They sense invaders in the body and alert other parts of the immune system about how to fight them, Keler explained.

The new treatment works by alerting the alerters: It lets the dendritic cells know that danger is nearby. Mittendorf said the treatment acts a bit like a spark plug when it kick-starts the immune system.

The dendritic cells then essentially put up signs to let other cells know which invaders to look out for and how to handle them, she said.

In the new Phase I study, researchers tested the injection treatment in 45 patients with advanced cancer who weren't responding to medication. Studies at this stage are designed to explore side effects and dosages of medications.

"The treatment was well-tolerated at all dose levels," Keler said. The only side effects were irritation and reddening at the site of the injection.

Keler said the treatment could potentially be used with other medications that enlist the immune system to fight cancer, but only in patients whose tumors have a specific kind of protein. "It's present in about 30 percent of melanoma cases and in a smaller percentage of various other cancer types," Keler said. But the treatment could be expanded to treat other kinds of cancer, he said.

The cost, Overwijk said, "will be completely determined by marketing and management of whoever might manufacture this drug." Making the drug itself won't be unusually costly, he added.

What's next? For now, "we are planning additional trials with our vaccine, focusing on combinations with other immunotherapy that may lead to significant clinical benefit," Keler said.